// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_COMPOSITOR_PAINT_CONTEXT_H_
#define UI_COMPOSITOR_PAINT_CONTEXT_H_

#include "base/logging.h"
#include "base/macros.h"
#include "base/memory/scoped_ptr.h"
#include "ui/compositor/compositor_export.h"
#include "ui/gfx/geometry/rect.h"

namespace cc {
class DisplayItemList;
}

namespace gfx {
class Canvas;
}

class SkPictureRecorder;

namespace ui {
class ClipRecorder;
class CompositingRecorder;
class PaintRecorder;
class TransformRecorder;

class COMPOSITOR_EXPORT PaintContext {
public:
    // Construct a PaintContext that may only re-paint the area in the
    // |invalidation|.
    PaintContext(cc::DisplayItemList* list,
        float device_scale_factor,
        const gfx::Rect& invalidation);

    // Clone a PaintContext with an additional |offset|.
    PaintContext(const PaintContext& other, const gfx::Vector2d& offset);

    // Clone a PaintContext that has no consideration for invalidation.
    enum CloneWithoutInvalidation {
        CLONE_WITHOUT_INVALIDATION,
    };
    PaintContext(const PaintContext& other, CloneWithoutInvalidation c);

    ~PaintContext();

    // When true, IsRectInvalid() can be called, otherwise its result would be
    // invalid.
    bool CanCheckInvalid() const { return !invalidation_.IsEmpty(); }

    // When true, the |bounds| touches an invalidated area, so should be
    // re-painted. When false, re-painting can be skipped. Bounds should be in
    // the local space with offsets up to the painting root in the PaintContext.
    bool IsRectInvalid(const gfx::Rect& bounds) const
    {
        DCHECK(CanCheckInvalid());
        return invalidation_.Intersects(bounds + offset_);
    }

#if DCHECK_IS_ON()
    void Visited(void* visited) const
    {
        if (!root_visited_)
            root_visited_ = visited;
    }
    void* RootVisited() const { return root_visited_; }
    const gfx::Vector2d& PaintOffset() const { return offset_; }
#endif

    const gfx::Rect& InvalidationForTesting() const
    {
        return invalidation_;
    }

private:
    // The Recorder classes need access to the internal canvas and friends, but we
    // don't want to expose them on this class so that people must go through the
    // recorders to access them.
    friend class ClipRecorder;
    friend class CompositingRecorder;
    friend class PaintRecorder;
    friend class TransformRecorder;
    // The Cache class also needs to access the DisplayItemList to append its
    // cache contents.
    friend class PaintCache;

    // Returns a rect with the given size in the space of the context's
    // containing layer.
    gfx::Rect ToLayerSpaceBounds(const gfx::Size& size_in_context) const;

    // Returns the given rect translated by the layer space offset.
    gfx::Rect ToLayerSpaceRect(const gfx::Rect& rect) const;

    cc::DisplayItemList* list_;
    scoped_ptr<SkPictureRecorder> owned_recorder_;
    // A pointer to the |owned_recorder_| in this PaintContext, or in another one
    // which this was copied from. We expect a copied-from PaintContext to outlive
    // copies made from it.
    SkPictureRecorder* recorder_;
    // The device scale of the frame being painted. Used to determine which bitmap
    // resources to use in the frame.
    float device_scale_factor_;
    // Invalidation in the space of the paint root (ie the space of the layer
    // backing the paint taking place).
    gfx::Rect invalidation_;
    // Offset from the PaintContext to the space of the paint root and the
    // |invalidation_|.
    gfx::Vector2d offset_;

#if DCHECK_IS_ON()
    // Used to verify that the |invalidation_| is only used to compare against
    // rects in the same space.
    mutable void* root_visited_;
    // Used to verify that paint recorders are not nested. True while a paint
    // recorder is active.
    mutable bool inside_paint_recorder_;
#endif

    DISALLOW_COPY_AND_ASSIGN(PaintContext);
};

} // namespace ui

#endif // UI_COMPOSITOR_PAINT_CONTEXT_H_
